Gum arabic1. c tnh v cu trcGum arabic l mt cht keo thc phm c ngun gc t t nhin c chic xut t nha ca loi cy acacia v c s dng lm nguyn liu v ph gia thc phm t hng ngn nm trc. Hin nay c cc loi gum arabic thng mi c sn xut ch yu t hai ging, gi l Acacia senegal v Acacia seyal. Chng c nhiu trng thi khc nhau nhng trng thi c tinh ch, dng bt vn l ph thng nht.Gum arabic c xem l mt polysaccharide arabinogalactan c mc phn nhnh v khi lng phn t cao, ha tan rt cao ( 1g/2ml nc ), to ra dung dch c nht thp. Khi so snh v nht vi dung dch guar gum, xanthan gum v lambda carrageenan nng 1%, t nht tng t vi cc keo a nc ny ( 3000- 3500 mPa.s ) th gum arabic phi c nng ln n 45%. nht thp ny l do cu trc phn nhnh hnh cu ca chng cn tr s hnh thnh cc lin kt ngang hoc lin kt hydrogen vi nc v cng chnh cu trc ny gip cho chng chng chu c s thy phn trong mi trng acid, chng li s thoi ha iu kin nhit cao cng nh s xc tc enzyme.Tt c cc phn t gum arabic cha cng mt nhm ng ging nhau: galactose, arabinose, rhamnose v acid glucuronic c trung ha tng phn bi mui ca calcium, magnesium, potassium v sodium. Trong phn t ca chng c t nht hai phn on c khi lng phn t khc nhau. Trong phn on c khi lng phn t ln nht, on polysaccharide arabinogalactan(AG) c gn vo mt khung c tnh cht phn t protein hnh thnh phn on arabinogalactoprotein (AGP), tuy rng phn on AGP ch chim mt lng nh trong gum nhng iu ny gii thch chop tnh cht hot ng b mt v c s dng ging nh cht nh ha ca gum arabic. Tuy nhin s phn on cha khung c tnh cht protein trong gum t Acacia seyal t hn gp i loi gum t Acacia senegal, do ngi ta thng khng dng gum t Acacia seyal cho mc ch nh ha.2. ng dng trong thc phm2.1 Trong sn xut koArabic khng dng nh mt cht to c trong sn phm dng lng do c tnh to nht thp. Tuy nhin trong cc sn phm cha ng hoc ng thay th c hm lng cht kh cao, chng c vai tr ni bt. Chnh iu ny chng c ng dng trong cc sn phm ko khun, ko vin, sn phm ko c dai c o hoc khng o ng, sn phm ko khng ng.Hm lng arabic c s dng khc nhau trong tng sn phm. V d mt cng thc cha 35% gum arabic, 30% ng saccharose, 25% ng glucose, khong 10% nc, thm mu, hng liu l thng c dng sn xut loi ko c cu trc dai, hi cng. Sn phm ny c u im l c th ko di thi gian nhai trong ming, khng dnh rng v gii phng hng v tt. Cn nu mun sn xut ko c cu trc mm hn th gim hm lng gum arabic xung.2.2 Sn phm h nhTuy gum arabic khng c xp vo cht nh ha nhng trong thc t chng c s dng nh cht nh ha v cht n nh trong cc h nh ha du trong nc. Tnh cht ny l do trong phn t AGP ca gum arabic c thnh phn cha c tnh ca protein, c tnh cht hot ng b mt, to cho gum arabic c gi tr cn bng a nc k nc (HLB) v s hnh thnh mt lp mng mng bao quanh cc git du.Do hng liu, mt s cht mu, vitamin..khng ha tan hoc phn tn trong nc nn khng th s dng chng trong sn xut nc gii kht nn ngi ta s dng tnh cht to nh ca gum arabic nh ha chng, to ra cc sn phm nh tng m c c th phn tn trong nc. Sn phm ny c pha vo trong cc sn phm nc gii kht nh l nguyn liu to hng, to mu, b sung dinh dng..,c bit sn phm nh tng ny thch hp trong cc loi nc gii kht c pH thp v gum arabic bn trong mi trng acid.K thut to v lm bn nh tng: dung dch gum arabic c trn vi pha du trong thit b trn tc cao to ra h nh ha. Sau h nh c a vo trong thit b ng ha to ra cc vi ht c kch thc ng nht, gip lm tng bn ca h nh.2.3 Trong sn phm o v ln vinC nhiu loi ko c nhn khc nhau nh: hnh nhn, chocolate, ht iu...c o bng mt lp v ng hoc chocolate. C 3 phng php o khc nhau ty vo loi nhn, bn cht ca lp o v cu trc yu cu l: lp o cng, lp o mm v lp o chocolate.Do tnh cht to mng mongrcuar gum arabic m n c s dng trong cc dch ng o lm tng hiu qu o v ci thin mt s tnh cht ca h nhn bn trong. V d khi sn xut ko vin c nhn chocolate( nhng loi cha cht bo cao), lp o ng c cha arabic s to ra nhng mng mng ngn chn s thm cht bo t trong nhn ln b mt to ra hin tng loang l cht bo v kh nng to mi v i gt do cht bo b oxi ha.Ngoi ra gum arabic cn to cho qu trnh o d dng, ng bm dnh tt hn, lp o ng bng phng c n hi linh hot lm b mt vin ko khng b nt gy. Mt t l gum arabic 3-5% trong dung dch ng saccharose 80% cht kh c th dng to mt lp o ng cng, gum arabic cn gip lm gim s hnh thnh cc tinh th ln ca ng. Vi sn phm c o chocolate, mt dung dch gum arabic 30-35% s c o lm bng, sng cho cc lp o ngoi cng, sau n c bao ph bng mt lp sp shellac ngn s ht m ca gum.2.4 Sn phm bao vi nangGum arabic c ng dng rng ri trong cng nghip vi kh nng to thnh cc mng li hoc mng mng bao quanh nhng ht du rt nh, sau to ra cc vi ht rn v y l mt k thut gi l bao vi ht.Do hng liu l cc hp cht tan trong du , khng tan trong nc , d b oxi ha..nn gum arabic c dng bao vin cc git du hng liu li ti, chuyn chng thnh dng bt rn nhm mc ch: Hn ch s oxi ha hng liu trong thi gian bo qun( to mng) Gip hng liu c th phaanh tn trong nc trong qu trnh ch bin thc phm Gim s tht thot hng liu trong qu trnh ch bin c gia nhit K thut bao vin: dung dch gum arabic(pha nc) c trn vi hng liu(pha du) trong thit b trn tc cao to ra h nh ha. Sau h nh c a vo thit b ng ha to ra cc vo ht c kch tht ng nht. Cui cng, hn hp ny c em sy phun to thnh sn phm dng bt rn c kch tht ht ng u. y chnh l cng ngh to ra sn phm hng liu dng bt.Alginate1. c tnh v cu trcAlginates l t ch chung cho mt s hp cht mui ca acid alginic thu c t mt s loi to nu Laminaria hyperborea, Laminaria digitata, Lamimaria japonica, Macrocystis pyrifera...Trong qu trnh sn xut, acid alginic c chit xut t cc loi to ny nhng do n khng bn, d b t phn nn ngi ta chuyn c thnh cc hp cht mui alginate khc nhau, c tnh bn v c th tan trong nc. Trong s ny th sodium alginate l hp cht c s dng ph bin.Trong thc phm, alginates c vai tr l cht to c, cht n nh, cht to gel, cht to mng. Sn phm alginates thng mi c nhiu kch thc khc nhau nhng ph bin l dng bt c mu trng n nu vng.Trong alginate cc n phn t M, G c th lin kt vi nhau to thnh 3 loi khi: +Khi M: gm cc n phn t M lin kt vi nhau+ Khi G: gm cc n phn t G lin kt vi nhau+ Khi MG: gm cc n phn t M,G lin kt lun phin nhau1.1 S ha tan ca alginateAlginate ho nc nhng ha tan chm trong nc nn khi cho chng vo dung dch th chng rt d vn cc. ngn chn tnh trng ny alginate thng c tr vi ng ct phn tn s b cc ht, bt alginate trong ng hoc chng c phn tn trong nc kt hp vi lc khuy, ct trn tc cao.Hm lng cht kh, hm lng ion, v d nh cng ca nc, nhit ca mi trng ha tan cng nh hng n kh nng ha tan ca alginate.1.2 nht ca dung dch alginate nht ph thuc trc tip v chiu di chui ca n. Alginate c chui cng di th nht cng cao. Mt s thnh phn khc cng lm tng nht nh hm lng ng cao, mt s mui..Khi cho vo 1 lng nh ion Ca2+ s lm Tng nht t ngt. Khi c lc khuy, ct tc dng ln dung dch th nht s gim ng k.1.3 S to gel ca alginate